Two of the runners, a mother-daughter team from Albuquerque, were very close to the first explosion. Abby Marrs, 25, said she had just completed the race and was recovering in a restaurant a block away when the blast went off at the finish line.

"It shook like really loud thunder, and that's how we knew something happened," she said “We could see through the big glass windows. We could see people screaming and running away."

Marrs said her mind immediately went to her mother, who was still in the race.

"I was waiting for my mom, who I knew was finishing at that time," Marrs said.

Marrs ran out into the smoky street, but it was already blocked off by police and emergency responders securing the blast zone.

"I was kind of panicking. I was only about a block away, but even that soon afterward, they weren't letting anyone towards there at all."

Her mother, Sarah Hartford, also a resident of Albuquerque, turned out to be OK. Marrs said her mother finished seconds ahead of the blast.

Hours after the explosions, Marrs described the streets of Boston like something out of a war zone.